The burgundy 6-pack of Studiofoam Pyramids from Auralex are acoustical panels designed to eliminate standing waves, flutter echoes, and reduce unwanted reflections and room ring for recording studios, broadcast facilities, churches, schools, and home theater applications. Each panel is 2 x 24 x 48", so for 6 panels you get a total of 48 ft² of coverage.
The foam panels are long-lasting and won't crumble. In addition, they can be attached to a wall or ceiling to treat medium-sized areas and effectively kill standing waves and tame the full frequency bandwidth in virtually any acoustic environment.